Emily Belli, Tom Bird, Zhao Deng, Nate Ferraro, Valerie Izzo, Lang Lao, Brendan Lyons, Orso Meneghini, Phil Snyder, Gary Staebler, Alan Turnbull and Ron Waltz attended the 56th Annual Meeting of the APS Division of Plasma Physics in New Orleans, and gave presentations on their recent research. Zhao Deng, a Peking University graduate student working at GA with Ron Waltz, presented an invited talk on “Testing the High Turbulence Breakdown of Low-Frequency Gyrokinetics Against High Frequency Cyclokinetic Simulations”. In addition, Tom Bird and Brendan Lyons, who began postdoctoral research at GA in early October, presented invited talks on their dissertation research at IPP Greifswald and Princeton University.
A general new pseudo-spectral method, suitable for treatment of differential and integral operators on a truncated energy domain, has been developed in order to more accurately treat advanced collision operators in kinetic simulations. The method turns out to be a generalization of the Legendre and Laguerre pseudo-spectral methods, reducing to the former in the limit of small energy truncation, and the latter in the limit of large energy truncation. Developing the pseudo-spectral method required symbolic algebra to avoid precision loss. In this process we have derived a new set of orthogonal polynomials and associated recursion relations.
At the opening ceremony of the 25th Fusion Energy Conference in St Petersburg, Russia, the IAEA presented the 2014 Nuclear Fusion Award to Phil Snyder of the GA Theory Group. The award recognizes the paper having the most impact over the past two years. The paper is “A first-principles predictive model of the pedestal height and width: development, testing and ITER optimization with the EPED model.” (P.B. Snyder, R.J. Groebner, J.W. Hughes, T.H. Osborne, M. Beurskens, A.W. Leonard, H.R. Wilson and X.Q. Xu, Nucl. Fusion 51, 103016 (2011)). Details are given in a recent press release at http://www.marketwired.com/press-release/ga-physicist-wins-international-energy-research-award-1957311.htm.
In addition, the GA theory group presented five papers at the IAEA meeting. Eric Bass presented his recent work on “Fusion Alpha Loss in ITER with Local Marginal Stability to Alfven Eigenmode.” Valerie Izzo and Phil Snyder gave oral presentations on “The Role of MHD in 3D Aspects of Massive Gas Injection,” and “Super H-Mode: Theoretical Prediction and Initial Observations of a New High Performance Regime for Tokamak Operation,” respectively. Orso Meneghini made a presentation, “Integrated Modeling of Tokamak Experiments with OMFIT,” and Gary Staebler gave a presentation on “Limit-Cycle Oscillations and L/H Transitions from Two-Dimensional Mean-Field Momentum Transport Equations.”
Two postdoctoral researchers, Dr. Brendan Lyons and Dr. Thomas Bird, arrived this week to begin work with the GA Theory group. Dr. Lyons recently received his PhD from Princeton University, where he worked with Steve Jardin to develop methods for calculating closures for fluid equations from drift-kinetic equations. At GA, he will be working with Nate Ferraro to calculate non-axisymmetric response in RMP ELM-mitigated regimes. Dr. Bird was an undergraduate at U. Wisconsin Madison working on ballooning stability in non-axisymmetric geometry with Chris Hegna before pursuing his doctoral degree with Per Helander at IPP Greifswald. He will be working with Jeff Candy at GA on edge gyrokinetic stability and transport. Both Dr. Lyons and Dr. Bird will be presenting the results of their graduate research in invited talks at this year’s APS-DPP meeting in New Orleans.
The GA Theory group hosted workshops this week for the Edge Simulation Laboratory (ESL) and Advanced Tokamak Modeling (AToM) projects. Collaborators from ORNL, LLNL, UCSD, and CompX were in attendance and collaborators from LBL attended remotely. The ESL project develops and applies numerical tools for kinetic studies of the edge, pedestal, and scrape-off layer plasma. ESL is actively developing and enhancing COGENT, a continuum kinetic code for treating both the edge and SOL region in diverted geometry, as well as NEO, a comprehensive neoclassical code for the closed flux region, and CGYRO, a gyrokinetic code aimed at treating the high collisionality edge region efficiently. Plans for modeling 3D MHD edge response and neoclassical transport in 3D geometry, as well as enhancing the EPED pedestal model, were also discussed at the workshop. AToM is a new SciDAC project aimed at developing tools and workflows for integrated modeling with high-performance computing components. Coupling of high performance computing components will be accomplished through the IPS framework developed as part of the SWIM SciDAC. Workflow management, data management, and visualization will be done using the graphical user interface and scripting environment, OMFIT, developed at GA for managing and automating integrated modeling tasks. The AToM project aims to facilitate workflows for physics studies that require integrated modeling, such as turbulent transport in an evolving magnetic equilibrium, self-consistent transport across the core, pedestal and SOL regions, and runaway electron generation during a thermal quench, and plasma-RF coupling. Both the ESL and AToM projects are partnerships supported jointly by the DOE Offices of Fusion Energy Sciences (FES) and Advanced Scientific Computing Research (ASCR).
These highlights are reports of research work in progress and are accordingly subject to change or modification